Internal combustion engines of the type mentioned above are intended to be used for driving different kind of hand held tools such as chain saws and power cutters. In order to decrease the vibrations transferred from the engine to the handle portion the engine is usually separated from the handle portion by means of a flexible damping arrangement and to further decrease the vibrations usually certain details of the mass system, such as the carburettor, the air filter system and the fuel tank are usually secured to the handle portion. This also decreases vibrations for the carburettor thereby increasing carburettor reliability. Consequently there is a demand for flexible connections between the different details on the handle portion and the engine but since these connections have to be secured to the engine at a rather concentrated area the assembling procedure becomes complicated. In particular the assembling procedure for securing the different intake ducts for mixture and air to the cylinder of the engine is time consuming and it is also difficult to dismount the arrangement when making maintenance and repairing the hand held tool. Further there is a need for a more stable and reliable fastening arrangement for the different ducts.